Arduino OLED Thermometer and Hygrometer With DHT11 for Beginners

Introduction: Arduino OLED Thermometer and Hygrometer With DHT11 for Beginners

Hello ! I'm going to show you how to make an Arduino OLED thermometer and hygrometer* with DHT11.

The OLED we will use today is 1.3″ inch in size, features 128×64 pixels and uses the SPI Bus. On the next step you will find more useful information about the OLED tech and this display.

We will use the u8glib library to communicate with our display. This library has many available parameters with it you can display numbers, letters, bitmaps and other symbols on OLEDs and graphic LCDs also it works for E-ink displays.

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* A hygrometer /haɪˈɡrɒmɨtər/ is an instrument used for measuring the moisture content in the atmosphere. - Wikipedia

Step 1: Info About the OLED Display and Tech

An organic light-emitting diode (OLED) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light in response to an electric current. This layer of organic semiconductor is situated between two electrodes; typically, at least one of these electrodes is transparent. - Wikipedia

The one I use is produced by Waveshare. Its 1.3″ inch in size, features 128×64 pixels and uses the 4-wire Serial Peripheral Interface Bus. It is monochrome blue in color also it consumes 0.04 W of energy which is one tenth that is required to run traditional 16x2 LCD display.

The OLED could be modified (soldering required) to communicate with different Bus, like a I2C or a 3-wire SPI, by moving one of the two resistors which can be found on the back of the display board. They are marked with 0s, check the pic above.

Changing the Bus from a 4-wire SPI to a I2C or a 3-wire SPI:

I2C - move BS1 resistor on 1 but keep BS0 on 0 as it is.

3-wire SPI - BS1 must be 0 and BS0 on 1

Step 2: Info About DHT11

The DHT11 is a basic, ultra low-cost digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air, and spits out a digital signal on the data pin (no analog input pins needed). Its fairly simple to use, but requires careful timing to grab data. The only real downside of this sensor is you can only get new data from it once every 2 seconds, sensor readings can be up to 2 seconds old.

Step 4: Connecting the Sensor and the OLED

Now take a look on the schematic above, plug in the display and the sensor into the breadboard. Then connect the negative and positive voltage pins of both DHT11 and the OLED to the ground and +5v pins of the Arduino UNO board with jumpers.

Then take one jumper and connect the output pin of the sensor to A0 of the Arduino board.

Connect the OLED pins: DIN to pin 13; CLK to pin 11; CS to pin 10; D/C to pin 9 and RES to pin 8 with the rest of the jumpers. 13, 11, 10, 9 and 8 are the SPI Bus of Arduino UNO they are also the ICSP connector under the microcontroller.

Once you connect them you can upload the code to the board (you can do that before connecting the sensor and the display).

Step 5: Upload the Code

This step is easy, just download one of the two .INO files, named Fahrenheit (measures in F) and Celsius (measures in C), and open it with the Arduino IDE then upload the code to the Arduino board.

If you don't like the current font you can change it simply by editing the code. You can find all supported fonts here.

If you don't have Arduino IDE click here to download it. Then install it.

Libraries you will need: DHT and u8glib download the libraries and then unzip them at /Program Files(x86)/Arduino/Libraries (default).

thank you Konstantin, i tried to make the project with dh22, nothing happens after uploading the sketch, edited the sketch for dht22 already.. , verified pinouts , i use the same oled using 5v out..any ideas???

thank you Konstantin, i tried to make the project with dh22, nothing happens after uploading the sketch, edited the sketch for dht22 already.. , verified pinouts , i use the same oled using 5v out..any ideas???

Thanks for the AWESOME instructable, it was simple and super easy to follow. Although it might just have been a problem on my side, I wanted to point out that the code for celsius shows the input pin of the dht11 as A5, and not A0. Sorry if it was a problem from me ;D

Nice little project. Why don't you use the DHT22 instead of the cheaper DHT11? The DHT11 has a very restricted humidity range and is not so accurate. As soon as the weather starts becoming rainy, you will have exceeded the DHT11's range of 20 - 80% humidity. The DHT22 goes from 0 - 100% humidity (non-condensing). In my opinion the DHT22 should be used for most environments.

Dear Mr KD, If I could bring your attn to Step 4. You say download the INO file, open it with Arduino IDE then upload the code to the Arduino board. I believe Arduino needs to verify the file first before uploading to Arduino board. This happens to be where I'm stuck as each time I try to verify Arduino highlights the 4th line down "dht DHT:" and states 'dht' does not name a type. Am I missing something?

I'm beginning to feel like a pest KD. Hope you don't mind my questions. I see you use the larger OLED display while mine is the smaller .96" SSD1306 module. Do you think I need to change any wording in your sketch in order to get my OLED working? Nothing showing on my display after uploading the sketch is why I ask.

it looks very nice, I've never worked with OLED yet, I think I will give it a try.

But before I've a question about what you wrote, here:

"

The OLED could be modified to work with different Bus, like I2C or 3-wire SPI, by moving one of the two resistors which can be found on the back of the display board. They are marked with 0s, check the pic above.

Changing the Bus from 4-wire SPI to I2C or 3-wire SPI:

I2C - move BS1 resistor on 1 but keep BS0 on 0 as it is.

3-wire SPI - BS1 must be 0 and BS0 on 1

"

I don't understand what I have to do to make it working with your "Arduino OLED Termometer". Can you, please, give me more details, as I cannot see modifications on your pictures ?

Well, my display can communicate with one of the two Buses SPI(by default) or I2C, with Arduino. The SPI bus has two variants with 3 and with 4 wires while I2C is using 2 wires. SPI has higher speed than I2C.

So, all you have to do is to buy OLED display with SPI interface to make my "Arduino OLED...." Thermometer.

Great stuff Konstantin. I've been looking for a portable thermometer/ humidity gauge for in the house and outside. In your project it appears you supply the power through the arduino uno's usb connection? Do you think a 9v battery could be connected to the 5.5 x 2.1 barrel jack to supply power instead? This way the whole works could be fit into a small project box.

But the negative side is, the author used a whole Arduino. Which made it big and not compact.Should have use some "bare bone arduino". It would have little and can be used in real life. Like,.... in a car or in a room..